1. Technical Field
The present invention relates in general to explosive devices, and relates in particular to means for containing and controlling the forces of explosive devices.
2. Background Art
Expendable perforators are used in many applications and generally include an explosive charge associated with a projectile for driving that projectile against a target. Such perforators are used in well boring and barrier penetration, as well as in bomb dearmament and disposal applications.
These perforators often have problems associated with side and end loss of explosive force about the outer perimeter of the projectile. This is an especially critical loss for small perforators. To overcome this problem, many expendable perforators include a means for containing the explosive force of the detonated charge so that detonation energy is concentrated on accelerating the projectile in a forward direction.
However full capability of such expendable perforators for industrial and commercial uses has not been achieved because no economically feasible and operationally satisfactory device has been developed which is acceptable for use in or in proximity to areas where there may be personnel or property which is susceptible to damage. More specifically, the detonation of explosive charges in accomplishing a cutting or severing function causes the generation of dangerous flying fragments as well as an overpressure of blast effect, either of which is a source of possible injury to personnel or property in proximity to the blast. Attempts have been made to develop an explosive device which is shielded to guard against fragmentation and blast effect. For example, it has been proposed that in conjunction with a linear-shaped charge a relatively heavy metal shield be secured by bolts or rivets to a member to be cut or severed. This approach has been found to be unsatisfactory because it is unsuccessful in reducing the blast effect, and the securing devices are torn from their moorings, thus becoming very dangerous projectiles themselves.
Other designs for containment devices have included a shield for restricting the blast effect and for containing an energy absorbing means around the explosive charge and between that charge and the shield. However, this device is intended to perforate a workpiece by exploding a hole in that workpiece and does not drive a projectile through the workpiece. Accordingly, the device is not a tamper mass and merely confines an explosion and does not provide any tamper function. Furthermore, it does not include any projectile. Therefore, side and end losses are not of concern to this containment device. Furthermore, this device includes a shield which must be secured to the surface being penetrated in order to support the shield and energy absorbing means. Therefore, this design has a possibility of having a fastener subjected to the explosion and becoming a dangerous projectile hurled away from the surface toward people in the vicinity of the device. Even beyond this problem; however, is the problems associated with the requirement of attaching the device to an object being penetrated. This requirement is not significant if the device is used to penetrate a wall or the like. However, if the device is used to dearm a bomb dud, a requirement that the penetrator device be affixed to the object being penetrated presents serious problems because many bombs have antidisturbance devices in them. Therefore, mounting a dearming device on a bomb dud should require as little disturbance to that bomb dud as possible so that personnel are subjected to as little danger to bomb explosion via antidisturbance device activation as possible.